Process for the production of catalytically-active metallic glasses

ABSTRACT

Catalytically-active metallic glasses containing at least one element from a subgroup of the periodic system and at least one element from a main group of the periodic system. Process for the production of catalytically-active metallic glasses where the metallic glass is produced from at least one element from a subgroup of the periodic system and at least from one element from a main group of the periodic system. The metallic glasses are activated by self-activation or by an oxidative and/or reductive treatment. The catalytically-active metallic glasses can be used as hydration, oxidation or isomerization catalysts.

This is a continuation of pending prior application Ser. No. 080,198,filed on July 31, 1987, of Franzen et al., for PROCESS FOR THEPRODUCTION OF CATALYTICALLY-ACTIVE METALLIC GLASSES, now abandoned,which is a file wrapper continuation of application Ser. No. 833,237,filed on Feb. 27, 1986, now abandoned, which is a divisional ofapplication Ser. No. 051,183, filed on May 18, 1987, now U.S. Pat. No.4,727,202, which is a divisional of application Ser. No. 758,829, filedon July 27, 1984, now U.S. Pat. No. 4,735,789.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The invention relates to catalytically-active metallic glases, processof producing such metallic glasses and process of using such metallicglasses.

2. Prior Art

Certain amorphous metal alloys catalyze hydrogenation reactions, forexample, those of cyclohexane derivatives [G. V. Smith et al., J. ofCatalysis 83 (1983) 238] or of carbon monoxide (i.e., Fisher-TropschReaction) [A. Yokoyama et al., Chemistry Letters (1983), 195]. Thecatalytic action is based on the amorphous state of the metals. However,it has also been described that in the case of the system Pd₈₀ Si₂₀, nosignificant differences exist concerning the selectivity in the case ofhydrogenation reactions between the amorphous state and the crystallinestate [B. Giessen et al., Mater. Res. Soc. Symp. Proc., (1982), Vol. 18,255].

In the case of most examinations, the surfaces and the state of order ofthe catalysts consisting of amorphous metals have not been investigatedsufficiently, so that the comparison between amorphous and crystallinesystems is not of any significant meaning. It turned out, for example,that the catalytical effectiveness could not be deduced because of alack of knowledge of the connections between amorphous and crystallinesystems.

BROAD DESCRIPTION OF THE INVENTION

An object of the invention is to provide processes for the production ofcatalytically-active metallic glasses. Another object of the inventionis to provide such catalytically-active metallic glasses. A furtherobject of the invention is to provide processes for the use of suchcatalytically-active metallic glasses. Other objects and advantages ofthe invention are set out herein or obvious herefrom to one skilled inthe art.

The objects and advantages of the invention are achieved by theprocesses and metals of the invention.

It is to be noted that in the present terminology, metallic glasses areto have the same meaning as amorphous metals.

The invention involves a process for the production ofcatalytically-active metallic glasses from at least one element from oneof the subgroups of the periodic system and at least from one elementfrom one of the main groups of the periodic system. The metallic glassesare activated by self-activation or by an oxidative and/or reductivetreatment.

According to the process of the invention, the metallic glasses changein such a way that the transformation products, the nature of which hasnot yet been described exactly, show unexpected catalyticaleffectiveness. Possibly, amorphous and crystalline regions lie side byside in highly dispersed forms. It is further noteworthy that thecomposition of the surface in many cases is not the same as that of the(central) mass.

Starting out from amorphous alloys, catalysts according to the processof the invention can be produced which are not obtainable according tothe hitherto known methods and processes for the production of catalystsor from the corresponding crystalline alloys.

The advantage of using amorphous metals as a starting material for theproduction of catalysts according to the process of the invention rests,among other things, on the fact that the metals in their amorphous stateare distributed in an extraordinarily highly-dispersed manner; they maybe aggregations of only a few atoms. In the case of the processes forthe production of catalysts used hitherto, it is true that with regardto the degree of dispersions, great advances have been achieved,however, none of the industrially used processes leads to a similarlyhigh degree of dispersion as obtained by the process of the invention.

According to the invention, the catalytically-active metallic glassescontain at least one element from at least one of the subgroups of theperiodic system and at least one element from at least one of the maingroup of the periodic system. In the invention, the elements of Group VAare also counted as being in the main groups.

The metallic glasses according to the invention can contain an elementfrom Group IVA of the periodic system and at least one element of GroupIB, Group VA or Group VIII of the periodic system. From Group IV, theelements Ti and especially Zr, from Group IB the element Cu, from GroupVA, the element V (vanadium), and from Group VIII, the elements Co, Ni,Pd and especially Fe, are preferred.

The designation of the groups of the periodic system herein, and theaccompanying claims, is based on the Table "The Periodic System Of theElements" from "Roempps Chemical Dictionary," Vol. 4, 7th Ed., (1974),page 2557.

Suitable metallic glasses contain Zr and Fe, Ti and Fe, Zr and Cu, Tiand Cu, Zr and V, Ti and V, Zr and Ni, or Ti and Ni, and preferably theyconsist of metals with the formula Fe₉₁ Zr₉, with the formula Fe₉₁ Ti₉,with the formula Fe₂₄ Zr₇₆, with the formula Fe₂₄ Ti₇₆, with the formulaNi₂₄ Zr₇₆ or Ni₂₄ Ti₇₆, with the formula Cu₇₀ Zr₃₀ or Cu₇₀ Ti₃₀, withthe formula V₃₆ Zr₆₄ or V₃₆ Ti₆₄, or with the formula Ni₆₄ Zr₃₆ or Ni₆₄Ti₃₆.

The so-called metallic glasses, amorphous metals, glassy metals orvitreously-rigidified metals according to the invention are amorphousmetal alloys with a disarranged structure which are not located in thethermodynamic equilibrium. Metallic glasses are inclined torecrystallization whenever the reaction temperature of the catalyticconversion lies above the vitreous conversion temperature. As a resultof components of the alloy, with up to 5 atom percent, for example, ofmolybdenum or tungsten, the glass conversion temperature can be raisedso far that a stabilization of the actual catalyst is achieved withoutsignificantly influencing its activity. Stabilized, metallic glassesconsist, for example, of Zr or Ti, Fe and Mo, preferably with theformula (Fe₉₁ Ti₉)₉₅ -Mo₅ or (Fe₉₁ ZR₉)₉₅ -Mo₅.

The catalytically-active, metallic glasses can be used as such ascatalysts since they often activate themselves, partly with anenlargement of the surface; an example of such a metal has the formulaFe₉₁ Zr₉ or Fe₉₁ Ti₉.

It can, however, also be effective for various metallic glasses, forexample, Ni₆₄ Zr₃₆ or Ni₆₄ Ti₃₆, to conduct catalyst activation--such iswithin the scope of the invention. Such catalyst activations compriseprocesses such as treating with acids, effectively diluted acids,preferably aqueous HNO₃, in order to remove layers of oxide, thensubsequently treating with oxygen and after that treating with hydrogen.Consequently, the activation consists of treatment in an oxidizingatmosphere and subsequently treatment in a reducing atmosphere.Corresponding to the intended purpose of use, the treatment can also bereversed.

The metallic glasses, therefore, amorphous metals of the invention arealso suitable as starting products for catalysts without carriers. Forexample, one of the phases can be convert by chemical conversion in sucha way that it acts like a carrier in the conventional sense. As apossible disadvantage, there is a smaller specific surface which resultsfrom the various production processes.

The metallic glasses can be produced in known manners, for example, bythe melt spinning process, as flat or separated lamellae, and by thesplat-cooling process.

It turned out, however, that the ribbons obtained according to themelt-spinning process are also easily reduced to powder at lowtemperature and so can also be used in powdery form. Metallic glasses oramorphous metals, however, can also be produced directly as a powder.From ribbons or foils of metallic glass or amorphous metal, moldedbodies, for example, filles of columns, can also be produced and thenactivated to a catalyst state, being used as such.

In a series of cases, for example, with Cu₇₀ Zr₃₀ or Cu₇₀ Ti₃₀, thecatalysts from metallic glasses show activity already at temperatureslower than the corresponding catalysts based on crystalline startingmaterial. It is important that the reaction temperature be sufficientlylower than the glass conversion temperature of the metallic glass.

The metallic glasses of the formula Cu₇₀ Zr₃₀ can be activated in ahydrogen stream and then are suitable as hydration catalysts, forexample, for the hydration of 1,3-butadiene. For this reaction, it isadvantageous to reduce the metallic glasses with the formula Cu₇₀ Zr₃₀for about 2 to 8 hours in a hydrogen stream at 160° to 240° C. Duringthe hydration a ratio of butadiene to hydrogen of 2:1 to 1:1 and atemperature of 90° to 200° C., preferably 95° to 130° C., is maintained.

The catalysts produced according to the invention from the metallicglasses are suitable for hydrogenation reactions, for example, thesynthesis of ammonium from hydrogen and nitrogen, of hydrocarbons fromolefins or hydrogenation from nitroaromatics, for example, of cyclichydrocarbon, such as toluene, and for isomerizations, for example,methylcyclopentane.

By way of summary, the invention involves catalytically-active metallicglasses composed of at least one element from Group IVA of the periodicsystem, for example, Zr or Ti, and at least one element from Group IB,for example, Cu, or Group VA, for example, V, or Group VIII, forexample, Co, Ni, Pd or Fe. The metallic glasses have been self-activatedor activated by an oxidative and/or reductive treatment. The metallicglasses can be used as catalysts, for example, for hydrogenation,oxidation or isomerization.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, all ratio, proportions, parts and percentages are on aweight basis unless otherwise stated herein or otherwise obviousherefrom to one skilled in the art.

EXAMPLE 1 Synthesis of Ammonium From Nitrogen and Hydrogen

For the conversion, a gas of 75 percent of hydrogen and 25 percent ofnitrogen was used. The gas mixture was free of carbon monoxide. Thepressure was 9 bar. In a microcontinuous reactor, 2 g of catalyst wasinserted. The length of the catalyst bed was 20 mm, and the through-flowquantity was between 20 and 200 micromole sec⁻¹.

                  TABLE I                                                         ______________________________________                                                   Equilibrium turnover                                                          nanomole sec.sup.-1                                                Starting material                                                                          380° C.                                                                         400° C.                                                                        420° C.                                                                       Remarks                                  ______________________________________                                        Conventional Halder-                                                                       250      450     700    after 2000                               Topsoe catalyst                      hrs. not                                                                      stable                                   Fe.sub.91 Zr.sub.9 -crystalline                                                            800      1400    2000   stable                                                                        after 2000                                                                    hrs.                                     Fe.sub.91 Zr.sub.9 -crystalline                                                            140      260     400    stable                                                                        after 2000                                                                    hrs.                                     (Fe.sub.91 Zr.sub.9).sub.95 --Mo.sub.5                                                     180      330     500    stable                                   glass                                                                         Ni.sub.64 Zr.sub.36 glass                                                                  190      340     600                                             ______________________________________                                    

A nickel-zircon catalyst produced in the conventional manner showed noeffectiveness under these conditions. Under equilibrium turnover, theturnover is given per contact time standardized on the surface of thestarting materials (equals average duration of stay of a gas molecule inthe contact volume). The Halder-Topsoe catalyst is more sensitivevis-a-vis oxygen than the Fe₉₁ Zr₉ glass.

EXAMPLE 2 Synthesis of Ammonium

The conversion was carried out in an integral reactor made of stainlesssteel (40 cm long, 1.5 cm diameter) with purified gases. Analysis of thereaction products was done by means of an IR-gas analyzer. The pressurewas 4 bar. The total through-flow of gas was 30 to 40 ml_(N).min⁻¹ witha catalyst quantity of 8 to 10 g. The ribbons of metallic glass oramorphous metal were degreased and cut into pieces of a length of 1 to 2cm.

                  TABLE II                                                        ______________________________________                                                                Conversion grade η =                               Starting Material                                                                           Temp., °C.                                                                       ##STR1##                                             ______________________________________                                        Fe.sub.91 Zr.sub.9, amorphous                                                               350°                                                                             0.001704                                              Fe.sub.91 Zr.sub.9, crystalline                                                             350°                                                                             0.001309                                              Fe, pure crystalline                                                                        380°                                                                             0.000144                                              Fe.sub.91 Zr.sub.9, amorphous                                                               380°                                                                             0.005089                                              Fe.sub.91 Zr.sub.9, crystalline                                                             380°                                                                             0.004801                                              Fe, pure crystalline                                                                        450°                                                                             0.00835                                               Fe.sub.91 Zr.sub.9, crystalline                                                             450°                                                                             0.03268                                               Fe.sub.24 Zr.sub.76, amorphous                                                              450°                                                                             0.08170                                               Fe.sub.24 Zr.sub.76, amorphous                                                              380°                                                                             0.002880                                              ______________________________________                                         Note:                                                                         Ratio N.sub.2 :H.sub.2 = 1:2                                             

That alternating effects exist between the metals in the actualeffective catalyst is shown in the comparison of the conversion figuresfor the ammonium synthesis in the case of the system iron-zirconium.Whereas pure iron does not result in an active catalyst at 350° C., Fe₉Zr₉₁ and Fe₂₄ Zr₇₆ glasses form active catalysts. Whereas Fe₉₁ Zr₉ ismore active at 400° C. than Fe₂₄ ZR₇₆, Fe₂₄ Zr₇₆ surpasses the activityof Fe₉₁ Zr₉ at higher temperatures. Many highly active catalytic systemscan be obtained by way of amorphous metals.

EXAMPLE 3 Hydrogenation of Ethylene

The investigation was carried out in a circulatory reactor, and theproducts were analyzed by means of gas chromatography. The metallicglasses or amorphous metals were used as strips of about 1 cm lengthafter they had been degreased. The reaction mixture consisted ofethylene and hydrogen. Amorphous Ni₆₄ Zr₃₆ was first treated withdiluted nitric acid, then treated with oxygen and subsequently treatedwith hydrogen. After this pretreatment, the material showed catalyticactivity. Fe₉₁ Zr₉ glass showed no activity even after the pretreatment.Cu₇₀ Zr₃₀ glass showed a clear enlargement of its surface andextraordinary catalytic activity by means of treatment with hydrogen.

                  TABLE III                                                       ______________________________________                                        Catalyst       Reduction    Activity                                          ______________________________________                                        Cu.sub.70 Zr.sub.30                                                                          200° C.                                                                             very active                                       amorphous      H.sub.2, 4 hrs.                                                                            even at                                                                       80° C.                                     Cu.sub.70 Zr.sub.30                                                                          200° C.                                                 crystalline    H.sub.2, 4 hrs.                                                                            --                                                               H.sub.2, 8 hrs.                                                                            --                                                Cu             200° C.                                                                             --                                                               H.sub.2, 4 hrs.                                                ______________________________________                                    

With amorphous Cu₇₀ Zr₃₀, after activation at 200° C., a parallelquantitative conversion was measured in 24 minutes. In the same periodof time, the conversion already was 40 percent at 80° C. The differencebetween amorphous and crystalline starting material showed itself veryclearly in the case of hydrogenation of ethylene by means of Cu₇₀ Zr₃₀.Only the amorphous starting material resulted in an active catalyst.

EXAMPLE 4 Oxidation of Toluene

The conversion was carried out with a micropulse reactor at 300° C. Thereactor was coated with 2 g of amorphous V₃₆ Zr₆₄, which previously hadbeen treated with diluted HNO₃. A stream of air was saturated withtoluene and was passed through the micropulse reactor. After 2 hours,the catalyst had activated itself; per passage, 12.5 percent of thetoluene quantity used was oxidized into benzoic acid.

Under identical conditions, a V₂ O₅ catalyst on SiO₂ resulted in aconversion of 8.9 percent.

EXAMPLE 5 Hydrogenation of 1,3-butadiene

The reactions were carried out in a batch-circulation reactor and theproducts consisting of 1-butene, cis-2-butene, trans-2-butene and butanewere analyzed by means of gas chromatography. Amorphous and crystallinesamples of the composition Cu₇₀ Zr₃₀ were reduced at 200° C. for 4 hoursin a stream of hydrogen. This pretreatment caused an enlargement of thesurface of 0.015 m² /g on 0.56 m² /g with the amorphous sample, whilethe surface of the crystalline sample remained unchanged at 0.008 m² /g.

In order to be able to compare the activity of these samples, catalystquantities were selected such that equally large surfaces were presentin the reactor. Under identical conditions (T=130° C., p=0.8 bar,butadiene: H₂ =1:1), these experiments clearly showed that amorphousCu₇₀ ZR₃₀ was much more active than the corresponding crystallinesample.

                  TABLE IV                                                        ______________________________________                                                 0.12 g of amorphous,                                                                        8.0 g of crystalline                                   t (min). conversion, percent                                                                         conversion, percent                                    ______________________________________                                        25        4.59         0.0                                                    70       13.04         0.0                                                    90       16.76         0.0                                                    130      23.00         0.9                                                    130      26.00         1.1                                                    ______________________________________                                    

The selectivity as to butene was more closely investigated with theamorphous sample. In the case of 90 percent conversion, the selectivitywas 75 percent at 130° C. and 96 percent at 95° C.

EXAMPLE 6 Selective Hydrogenation of Butadiene

Dienes, especially 1,3-butadiene, cause deactivation of the catalyst inthe case of hydroformylation and form polymers in cracking operations.Therefore, they should be removed from olefins.

According to Example 5, 4 g of amorphous Cu₇₀ Zr₃₀ was used as catalyst.The hydrogenation of the mixture with the composition: 73 percent of1-butene, 24 percent of cis-2-butene and 3 percent of 1,3-butadiene, wasexamined at various temperatures. At temperatures higher than 90° C.,olefins were hydrated and large quantities of butane developed. At 75°C., butadiene was hydrated selectively and the product distributionconsisted of: 1.63 percent of butane, 1.35 percent of trans-2-butene,22.6 percent of cis-2-butene, 74.41 percent of 1-butene and 0.0 percentof butadiene, after a reaction time of 80 minutes. The hydrogenconcentration at the same time was 2 to 4 times greater than thebutadiene concentration. In this area, the hydrogen concentration had nogreater influence on the selectivity. The selective hydrogenation ofbutadiene in the mixture of ethylene and butadiene also took place atlower temperatures. The reaction temperature of 75° C. made possible thehydrogenation of butadiene with 93 percent selectivity on butene;ethylene was not hydrated at all. Higher temperatures however also causethe hydrogenation of ethylene.

What is claimed is:
 1. Process for the oxidation of toluene comprisingcatalytically oxidizing the toluene in the presence of a catalyticallyeffective amount of a catalytically-active metallic glass which consistsof V₃₆ Zr₆₄ or V₃₆ Ti₆₄, the metallic glass being first activated by anoxidative and/or a reductive treatment or being activated in situ. 2.Process as claimed in claim 1 wherein the metallic glass is V₃₆ Zr₆₄which has been activated by treatment with an acid and which is inribbon form.